Touch sensitive devices have become popular as input devices to computing systems due to their ease and versatility of operation as well as their declining price. A touch sensitive device can include a touch sensor panel, which can be a clear panel with a touch sensitive surface, and a display device, such as a liquid crystal display (LCD), that can be positioned partially or fully behind the panel or integrated with the panel so that the touch sensitive surface can cover at least a portion of the viewable area of the display device. The touch sensitive device can allow a user to perform various functions by touching the touch sensor panel using a finger, stylus, or other object at a location often dictated by a user interface (UI) being displayed by the display device. In general, the touch sensitive device can recognize a touch event and the position of the touch event on the touch sensor panel, and the computing system can then interpret the touch event in accordance with the display appearing at the time of the touch event, and thereafter can perform one or more actions based on the touch event.
Some touch sensor panels can include an array of touch regions or nodes formed at the crossing points between rows of drive lines and columns of sense lines. To sense a touch at the touch sensor, the drive lines can be driven by alternating current (AC) stimulation signals to capacitively couple with the crossing sense lines, thereby forming a capacitive path for coupling charge from the drive lines to the sense lines. The crossing sense lines can output touch signals representing the coupled charge or current. In some implementations, the stimulation signals used to stimulate each drive line can have the same frequency. However, to differentiate between the stimulation signals of the drive lines, each stimulation signal can have a different phase offset. While this technique can be used to effectively detect touch or hover events on smaller touch sensitive devices, the time required to scan the touch sensor panel for the touch or hover events can become undesirably long on larger devices.